Ultrasensitive photoelectrochemical aptasensing of miR-155 using efficient and stable CH3NH3PbI3 quantum dots sensitized ZnO nanosheets as light harvester

An ultrasensitive photoelectrochemical (PEC) aptasensor based on a novel signal amplification strategy was developed for the quantitative determination of microRNA (miR)-155. CH3NH3PbI3 quantum dots (QDs) functionalized ZnO nanosheets (NSs) were employed as the light harvester. Owing to the synergetic effect between CH3NH3PbI3 QDs and ZnO NSs, ZnO@CH3NH3PbI3 can provide an obviously increasing PEC signal by forming the heterojunction. Due to the larger steric hindrance, the sensitive decrease of the PEC signal can be achieved by the specific recognition between the primers and ssDNA of miR-155. In this sense, this developed aptasensor can achieve a high sensitivity (especially in the presence of the low concentrations of miR-155) and a wide detection range (0.01 fmol/L to 20,000 pmol/L). Under the optimal conditions, the proposed aptasensor offered an ultrasensitive and specific determination of miR-155 down to 0.005 fmol/L. This aptassay method would open up a new promising platform at ultralow levels for early diagnose of different miRNA.